Circling Downwards
by First Star of Night
Summary: [On Hiatus see profile for details] Charlie flies out to D.C. to help the NCIS team solve the murder of two former marines. But the job does not go according to plan when he meets up with Gibbs. NCISxNumb3rs crossover.
1. Chapter 1

**Disclaimer:** CBS owns both Numb3rs and Navy NCIS, including, but not limited to, characters, plot, and Charlie's hair.

**Author's Note:** This is my response to a challenge given by D. Lerious. Thanks for the idea! It is a crossover between Navy NCIS and Numb3rs. I will be switching between viewpoints, but hopefully I keep it clear from whom the section of the chapter is coming from. To add to the clarity, the periods in a row above a section show that the next section is to be told from an NCIS perspective, and the row of numbers indicate that the next section is to be told from a Numb3rs perspective. I hope you enjoy, and as always, read and review!

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"Gibbs. A word please."

Special Agent Leroy Jethro Gibbs looked up from his desk to find the director standing over it. "Now, Jen? I've got work to do on this case-" he whined before she cut him off.

"That's what I'm here to talk about, Jethro." She gave him the stare that he knew not to disobey. They walked off to her office before either one of them spoke again. When she spoke, Shepard was frank.

"You aren't getting anywhere on this case, Agent Gibbs."

"Not yet. But my team is working on it," Gibbs replied.

"And how long are you planning to let them 'work on it'? Like I said, you aren't getting anywhere on this case, and I preferably do not want to get more data with these numbers. Therefore, I am ordering your team to hire someone that can find a pattern to these numbers." Shepard looked down to her own work, obviously trying to end the conversation. However, Gibbs continued to watch her, a smirk trying to form on his face.

"And how long do I have to find this person? Who would drop all their work to come help us on patterns?"

"That is up to your team to figure out. However, I would check the Los Angeles area. I've heard good things about them. As for how long you have to find this person, I want him or her hired within the next twenty-four hours, here in D.C. in thirty-six," Director Shepard replied, not looking up. When Gibbs refused to leave in the next minute, she finally met his eyes. "Do you have any more questions, Jethro?"

"No. Of course not, Director."

"Good. Then you are dismissed."

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Special Agent McGee stared at the screen, his head resting on his hand, as he watched the numbers fill the screen. By now, though, they were blurred, and he wasn't really paying attention to them anymore.

"McGee! What are you doing?" Gibb's voice rang out through the room.

McGee sat up straight in response. "I was…uh…I was running through the numbers again, Boss. Seeing if I could find the pattern between them."

"What, for the fifty-seventh time?" Without waiting for a response, he continued. "Did you find anything new?"

"No, Boss. I haven't." His face started to redden. But what else was he supposed to do? Tony and Ziva were both off, talking to the families of the victims, and he had nothing else to do.

"Not the answer I wanted to hear, McGee, but it doesn't matter anyway. Stop doing that for now, and try to find someone that can come out and possibly find a pattern behind these murders," Gibbs ordered before he headed off to the elevator.

"Who am I supposed to find, Boss? A specific consultant?"

"Find a mathematician for all I care. Just follow the director's orders! I'm heading out for coffee." McGee followed him with his eyes until the doors of the elevator closed in front of Gibbs. Biting his lip, and not knowing how he would do it, he set off to work.

Half an hour later, Tony and Ziva returned, bickering about something or other, like they usually were. They both greeted him shortly before continuing with their argument, but he couldn't remember if he responded or not. He thought he found the perfect person, but who knew how well this guy actually did on these kinds of cases. For some reason, he had to continue looking on his background.

Gibbs returned not much longer after Tony and Ziva did, muttering about long lines at the local coffee house. Seeing McGee concentrate so much on the computer, he asked, "Did you find anyone yet?"

"Uh…yes, I have, Boss. I'm just finishing up his background."

"Well, pull him up, let's get a look at his file," Gibbs responded, sitting at his desk.

Putting the profile up, McGee began to talk about the consultant he had been looking at.

"Doctor Charles Eppes. Thirty, lives in Pasadena, California. He is a professor at a small college there, Cal Sci, teaching mathematics. Also, for about a year now, he has been consulting for the FBI office in L.A., using math to find patterns of suspects. He also has clearance with the NSA," he recited, giving as much information as he had.

"Sounds good, Probie, but what do we need to see the Doctor for?" Tony asked.

"To fulfill the director's orders, DiNozzo," Gibbs shot back. "He sounds as good as anyone, McGee. Call him up, see if he'll come out to D.C."

"Got it, Boss."

"And did you not hear the sarcastic tone I had when I said, 'Find a mathematician'?"

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"Eppes."

Special Agent Don Eppes answered his cell phone, expecting the call from Charlie. They were supposed to be surprising their father with a nice dinner, since neither one had been around much lately. Charlie was supposed to be pulling a few strings with an old student of his to get a nice table, and he was supposed to call when he was done. So he was surprised when an unknown voice responded.

"Doctor Eppes, this is Special Agent Tony DiNozzo of NCIS. We are sorry to bother you like this, but we would like to hire you as a consultant on one of our cases."

"Hang on, this isn't Doctor Eppes." Don felt a little weird referring to his brother as "Doctor Eppes", but he could live with professional courtesy. He felt even weirder at the fact that this Tony DiNozzo called _his_ cell phone asking for Charlie.

"It isn't? Oh…umm…could you hang on a second?" The voices on the other end of the phone became muffled. Don couldn't help but feel that Tony was quite rude, not even asking if he was in fact "Doctor Eppes" before launching into his little speech. But why would NCIS want to hire Charlie?

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"It isn't? Oh…umm…could you hang on a second?" Special Agent Tony DiNozzo put his hand up to the phone, trying to muffle the confusion that would be sure to start.

"Probie? I thought you said this was the phone for Doctor Eppes?" Tony shouted across they way.

"It is. Or, at least, I thought it was. Hang on…" Tony could see McGee's eyes scan the computer quickly before continuing. "Yeah, it says here that this is the phone number for Agent Eppes. Agent…oh. It's Special Agent Donald Eppes. They must be related."

Tony walked over, phone still in hand, and smacked McGee on the back of the head. "You think, Probie?" he asked.

Gibbs immediately came over, and whacked Tony on the back of his head. "Don't whack him, DiNozzo. Only I get to do that."

"What love we have here," Ziva observed from her corner.

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"Oh. It's Special Agent Donald Eppes. They must be related." Through the muffled sounds, Don could clearly pick that up. After all, he'd been hearing things like that ever since his parents were told that Charlie was a genius. He still heard these things, even though he had distinguished himself from Charlie, but high school was the worst time for that. As the agents at the other end of the line squabbled, Don couldn't help but remember some of the worst words he had ever heard in his life.

High school years were great, for the most part. Yeah, so his nine-year-old brother would be starting high school with him, but he could live with that. "Keep him out of trouble," his parents had said. And although he had to save his younger brother from a few bullies that first year, Don didn't need to worry about Charlie all that much. In fact, he tried to avoid him at all costs.

_Freshmen year had come and gone. The two of them had none of the same teachers, so no associations were made there. His brother tried to get his attention in the hallways between classes, but Don ignored him unless something was really bothering him. Charlie would have that hurt look on his face, and it stung to see him with it, but Don grew used to it. One hundred and eighty days of that look did that. Besides, as long as he played some basketball with him in the afternoon, Charlie didn't seem to mind. _

_Sophomore year ruined that. Suddenly, he had trigonometry, the same teacher that Charlie had the year before. The teacher quickly realized that, and expected Don to be just as good as his brother. The other students found out, and suddenly he was no longer the cool Don Eppes, just the guy with the freak of a brother. Don was determined to change that, and threw himself into his baseball, soon becoming the star of the team._

_Graduation was the absolute worst part of the four years. On a day where everything was supposed to be final, everything was supposed to be good, Don's world came crashing down. And although it was only a few seconds, Charlie was a high school graduate and he wasn't. He never got over that._

And now people were asking for Doctor Charles Eppes to help with a case, not the FBI agent himself. A pang of jealousy quickly shot through him, but he was able to get over it quickly. The two of them had grown closer than ever in the past year. Why shouldn't Don be proud of his younger brother?

Agent DiNozzo's voice pulled him out of his thoughts. "This is Agent Donald Eppes then, right?"

"Yes."

"Are you related to Doctor Charles Eppes?"

"Yes. Charlie is my brother." Again, the pang of jealousy shot through him, as he, once again, had to say that they were brothers. _I'm over that, though. I'm a separate person now. I'm proud of my younger brother._

"Would you mind giving us some contact information for you brother, Agent Eppes?"

"Actually, I would. Why do you want to talk to Charlie?"

"Well, NCIS is not allowed to talk to anyone that is not working on the case-"

"Not even the FBI?"

Don could hear Agent DiNozzo chuckle. He figured it would take a while to get some answers, so he settled into his chair, and began to mentally set up his interrogation plan.

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Gibbs was staring pointedly at DiNozzo, urging him to hurry up. DiNozzo glanced over at him, and a small chuckle escaped his mouth.

"Well, personally, even I am not at liberty to tell the FBI. However, my supervisor would be happy to answer any of you questions, Agent Eppes." Pulling the phone away from his ear, he motioned to Gibbs to take the phone.

Rolling his eyes, he took the phone. Instantly, he got down to business.

"Listen, Agent Eppes. My team has been working on a case for two weeks. Our killer has been leaving a code for us in numbers, but we have not been able to crack it. We know that Doctor Eppes consults for the NSA and the FBI on these kinds of things, so we want to hire him. Any other questions?" Gibbs didn't hear anything, so he continued. "Now, could I please get Doctor Eppes' contact information?"

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"Any questions?"

Don was too stunned to speak. Would it really be hard for Agent DiNozzo to give him that information? Sometimes he wished he had someone like Agent Gibbs on his team to give him straightforward answers.

"Now, could I please get Doctor Eppes' contact information?"

Don finally got over his shock in time to answer. Somehow, he got the feeling that he did not want to anger this Agent Gibbs.

"Well, his cell phone is currently off. But I will be speaking to him tonight, so I will mention it to him and have him call you."

The two of them exchanged information before Don hung up.


	2. Chapter 2

**Disclaimer:** Still don't own Charlie's hair. Or any other part of Numb3rs, either. Or Navy NCIS. CBS owns all of the characters, plot, and everything that goes with one of those two for both shows.

Thanks for all the reviews, you guys! I never thought that this story would get the attention that it did. Therefore, for all you wonderful reviewers, I decided to post this chapter earlier than I thought I would. Please continue with all the support you are giving! That means, when you're done with the chapter, review!

And, once again, a series of numbers above a section means the section is from a Numb3rs perspective, while the series of periods indicate the next section is from an NCIS perspective.

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"You know," their father piped up as they were eating dinner, "I was really starting to miss you guys. We haven't had dinner together for nearly two weeks. But if this is the kind of treatment I get, I may start asking you two to have more of these disappearances."

Charlie laughed along with his father, but Don was only able to smile. Knowing his father was joking made what he had to tell Charlie even harder.

Amid their laughing, Don barely heard his cell phone ringing.

"Eppes." He could hear commotion on the other end of the phone before Agent Gibbs spoke.

"So have you asked him yet?"

Don looked at his family. The two of them were still talking. He motioned he was going to go outside for a bit. They nodded, and he walked outside.

"Agent Gibbs, I was about to talk to him about it when you called."

"Well, tell him he has twelve hours to decide whether he's going to come or not!" Agent Gibbs responded before hanging up abruptly.

Don pulled the phone away from his ear and stared at it blankly. Did he really want his best consultant to work for _this_ guy?

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"Well, tell him he has twelve hours to decide whether he's going to come or not!" Hanging up the phone, Gibbs tried without success to control his frustration. _Why did McGee have to decide to take me seriously? Why did he have to hire a mathematician?_

"Uh, Boss? Is something wrong?"

"What makes you think something is wrong, McGee?"

"Well, you told Agent Eppes that his brother has twelve hours, but he really has eighteen. You hung up suddenly on another agent that isn't someone that works here."

"To answer your question, yes, something is wrong." He left the room before he could McGee could ask any other questions.

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Charlie couldn't believe what Don was telling him. NCIS wanted him to go to Washington, D.C. to work on a case there?

"So, basically, they need a mathematician to crack a code, they heard about me working for the FBI, and now they want me to consult for them on a case?"

"Basically, yeah."

"And they can't find someone closer to D.C. why?" Mathematicians were all throughout the country. Why ask somebody that was on the other side of the United States? It simply wasn't logical.

"They also heard about your work with the NSA. Other than that, I don't know why they want you instead of any other mathematician," Don responded. "The other thing is that Agent Gibbs wants your response within the next twelve hours."

Charlie thought for a while. School was out for the summer, so he had about two months available.

"Sure, why not?" _This could get interesting._

"So you are going to be gone for a long time again?" his father asked. "I wasn't serious about you disappearing again."

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McGee's head shot up when Gibbs' cell phone rang.

"Yeah, Gibbs."

McGee watched Gibbs' face in wonder as it changed from his usually emotionless look to upset before he spoke again.

"Okay, thank you, Doctor Eppes. Either Director Shepard or I will be at the airport to pick you up in the morning."

Hanging up, Gibbs looked more upset that McGee thought he would be, considering Doctor Eppes apparently decided to come out to D.C. "Anything wrong, Boss?"

"No! Everything's fine! I'm going to inform the director of Doctor Eppes' decision." And without further comment, Gibbs stalked off toward Shepard's office.

McGee couldn't help but wonder what this Doctor Eppes person could have done to anger Gibbs.

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"Okay, thank you, Doctor Eppes. Either Director Shepard or I will be at the airport to pick you up in the morning."

Charlie was about to ask who Director Shepard was, or what he was going to be specifically doing with whom, or any of the other questions whirling around his head, but Agent Gibbs hung up on him before he could ask any of them.

Charlie hung up his own phone in a bit of a daze. Was he just imagining it, or did Agent Gibbs really not want him to go? Was Agent Gibbs mad at him, or was there something else going on that put him in his bad mood? Or is that just the way he acts all the time? Don looked back at him from across the table, nodding, probably at the shocked look on his face. "I take it you had the same impression of him that I did?"

"I don't know. Did you get the impression that he really didn't want me to come, but he had to anyway? That he doesn't like me, even though he's never met me?"

Don shook his head, saying, "No. I just got the impression that he got right to the point, but he could be kind of rude in getting there. And that he's definitely not someone you want to anger."

Charlie stared at the beer bottle Don was holding. It was half empty, but Don had been drinking from that bottle for half an hour now. "Yeah, that too. But I think I might have already angered him, and I don't know why or how."

The two sat in silence, thinking about what was coming up. _Why should I be nervous? It will be just like when I first started consulting for the FBI. Prove to everyone that math can be used, help them solve the case, and be on my merry way home?_ But Charlie could only wonder why he didn't feel like it would be that easy.

Five minutes later, Charlie mumbled, "I'd better go start packing." Don nodded, staring off into space. Sighing, he trudged up the stairs to his room, and pulled out a large suitcase, as well as some clothes.

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"But I think I might have already angered him, and I don't know why or how." Don nodded in response to his brother's statement. Charlie might not know how or why Agent Gibbs was angry with him, but Don had a good idea why. Because he had felt it so many times himself.

What Charlie still didn't seem to understand was the fact that most people didn't like somebody who acted like a know-it-all. People liked to be right, but when somebody else was always right, they didn't like it. Even Don had felt this way toward his brother. He had never hated Charlie like some of his friends had. Brothers might dislike each other, but they don't truly hate each other. Besides, Don saw the faults in his brother that nobody else saw, the faults that made his brother human.

As he stared off into space, Don's protective feelings started to come out, and it was all Don could do to control them. It was almost like they were back in high school again, and people doubted Charlie because of his obsession with numbers. Now that he was an adult, Charlie was using his math abilities to teach others, which gave him at least a little bit of social interactions that he missed in school. He was also using math to help the FBI and NSA, benefiting the population as a whole.

Don couldn't be more proud of how far his brother had come as a person, even in the past year. Logically, Don knew that Charlie would be okay with Agent Gibbs and the other agents in D.C. But his big brother instincts were trying to resurface, and it was harder and harder to hold them back.

Charlie mumbled something around the lines of starting to pack, but Don could not remember if he responded or not. He had to be at the airport in a few hours to catch his flight, and Don had promised to drive him over. But right now, Don was lost in his thoughts, his debate over whether to play coworker or big brother with Charlie.

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He really did mean to start packing. Honestly. But he was laid out on the bed, and he made no move from his position. The room was a mess; clothes were laying on the chair, the desk, the bed, almost everywhere except the suitcase.

Charlie could hear the clock in the hallway ticking as the seconds passed, then minutes. Still, he didn't move. He could hear movement downstairs, but he couldn't figure out what was happening.

The movement became clearer and louder, and Charlie could figure out that somebody was walking up the stairs. He couldn't say he was looking forward to either his dad or brother telling him he was wasting time, so he finally stood up and started packing the clothes previously thrown around the room.

The person entered the room, but Charlie didn't see who it was; his back was facing the person. All he said was, "I know, I'm packing as fast as I can. I'll be down in a few minutes."

"There's no need to hurry, Charlie. We still have a few hours before we have to leave," Don's voice replied. Turning around, Charlie saw him with a smile on his face. Not a big, fake smile that seemed plastered there, but almost a shy, honest smile.

Turning back around to face the suitcase, Charlie merely nodded. He didn't want to say it, but Charlie was worried that if he didn't finish packing soon, he would never finish it.

Don headed off to the bed and sat at its foot. Charlie continued to pack, feeling Don's eyes follow him. Looking up, he asked, "What?"

"Is something wrong, Buddy?"

"Why do you think there's something wrong?" Charlie was surprised at the fact that Don caught on to his nervousness. But, of course, Don was used to interrogating suspects, and that included their body language, sometimes more than their spoken language.

"You're quieter tonight than you usually are, and you aren't full of the energy you usually possess. So what's up?"

"Honestly? I'm nervous. Usually, even when I start something new, I have at least one constant in the equation, one thing that stays the same from situation to situation. When I started high school, I was still living at home with you, Mom, and Dad. At Princeton, Mom came with me. When I started teaching at Cal Sci, teaching people that were the same age as me, I was still living at home. At the FBI, I was working with you. I'm going to be going off to Washington, D.C. I won't have you or Mom or Dad with me. I won't have any of the other agents from the office with me, or any of my friends. It will be a completely new equation with completely different variables. New people, new environment, new everything." Surprisingly, Charlie felt much better when he released all that from his mind.

"I can't believe I'm saying this, Buddy, but you are forgetting a variable," Don countered, a smug look on his face. Charlie shot him a quizzical glance. "The more surprising thing is that I caught on to it, even when you didn't. There's one constant throughout all of the situations that you mentioned above, the one constant that assures me that you'll be okay. In all of those situations, you have been Charlie Eppes. That's all the assurance I need to know that you are going to be fine. Even with Agent Gibbs."


	3. Chapter 3

**Disclaimer:** If you haven't figured it out by now, Charlie, DiNozzo, and all the characters of their respective shows belong to CBS. Though I desperately want Charlie's "pi" shirt.

**Author's Note:** I am completely blown away at how much you guys seem to love this story. Special thanks to the C2 Best of the Best Fanfiction for adding my story to their list, and a HUMONGOUS thank you to everyone that has reviewed this story. I'm trying to update this as often as I can, but as I'm trying to write a chapter of this story and a chapter of my other story at about the same time, and with my hectic schedule, there isn't a lot of time left for me to write. I'm glad you all like it, though!

The chapter was edited slightly 7/26/06. Nothing was changed plot-wise, but a miswrite was pointed out by Noma.

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"We are now in Washington, D.C. The weather is very warm, but there is a light rain falling. Currently, the temperature is 87 degrees."

The flight seemed to take much shorter than it should have for Charlie. Where had the five hours and twelve minutes gone? No matter where it had gone, no matter what he had been doing, he felt as though he boarded the plane maybe five minutes earlier.

"Thank you for flying Southwest Airlines. We hope that you continue flying with us in the future, and have a wonderful time at your final destination," the stewardess said over the speaker.

As the rush started to get out of the airplane, Charlie couldn't help but ponder why that was always said, especially the 'final destination' part. _Isn't the destination always the final part of the trip?_ he wondered. _Unless they count death as the final destination. But I can't imagine death being 'wonderful'._

As the crowd of people finally passed him, Charlie finally stood up and hit his head on the overhead compartment. Hoping this wasn't an omen of what was going to come in the near future, he grabbed his backpack out of the compartment above him and, rubbing his head with one hand, headed towards the front of the airplane and out the door.

Walking down the walkway, Charlie wondered how he would be able to find Director Shepard in the throng of people ahead of him. People were calling out to loved ones; others were on cell phones, calling a cab, most likely. If Director Shepard were there, he wouldn't be able to recognize her. Hopefully she would know whom to look for, by seeing his photo or something. If it were Agent Gibbs that came to pick him up-well, maybe it would be good to walk past him "accidentally".

"Doctor Eppes? Over here."

Charlie looked over to see a woman waving him over. She was wearing a cream-colored business suit, and her hair was cut short. She looked nice enough, though a bit on the serious side. She smiled at him politely, but she was scanning him, taking in his appearance.

Charlie began to blush, as he was wearing a pair of jeans with a hole in the knee (never bothered him before, nor had it bothered the FBI agents), as well as his pi t-shirt that was wrinkled from the flight. He was wearing a blazer that buttoned up half-way (_very_ stylish, according to Amita), so it was covering the shirt a little bit. But nothing covered up his mess of hair, where the curls were tangled together, possibly from him trying to get some sleep during the red-eye flight. Compared to Director Shepard, he was a mess.

_Well, _he thought, _if bumping my head on the overhead compartment wasn't an omen of what's to come, this probably is._

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Jennifer Shepard couldn't help but be surprised by the guy's appearance. Somehow, the fact that he had a Ph.D. made her believe that he would look somewhat professional. But the jeans, t-shirt, jacket, hair, and 5 pm shadow made him look almost like a college student trying to look "cool".

Some of the color drained out of his abnormally red face, though a bit of pink remained in his face. Maybe he had been blushing? She couldn't really tell.

"You must be Director Shepard," Dr. Eppes acknowledged, extending his hand.

She took it and shook it while replying, "Yes. So you are Dr. Eppes."

He nodded. "But please, call me Charlie."

"Charlie," she repeated, slightly startled, however much she tried to hide it. He was the first person she knew of who had a Ph.D. and yet did not go by the title "Doctor". "Well, Charlie, let's get your stuff, and head off to the office."

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"Well, Charlie, let's get your stuff, and head off to the office."

It was all Charlie could do to keep from groaning. Did Director Shepard not realize that Charlie had been up since seven o'clock the previous morning? It was now 5:30 Pacific Time, making it 8:30 Eastern Time. Sure, he could stay awake for days working on a math problem, but he wasn't doing that right now. Instead, he was headed to the NCIS office. Hopefully he would be getting involved with some exciting, or at least interesting work soon. He was afraid he would just doze off otherwise.

As the two of them waited for his suitcase, Charlie couldn't help but feel nervous. Director Shepard seemed to become agitated at how slowly the two of them were going. Finally, Charlie spotted the old, worn suitcase, and went to pick it up. Grabbing the handle, he pulled up the weight and head back over to Director Shepard.

"Shall we?" he asked her.

"We shall."

The two of them walked out to the parking lot, and Director Shepard led him towards a car with another woman leaning against it. She looked like she was Middle Eastern, and she was wearing a black sleeveless top. Her hair was pulled back into a bun, and she was wearing a baseball cap with the letters NCIS printed on the front.

"Charlie, I would like to introduce to you Special Agent David. Ziva, this is Dr. Charles Eppes, otherwise known as Charlie."

"It's nice to meet you, Agent David."

"Nice to meet you too, Charlie. May I take your luggage?"

Charlie handed over his suitcase to Agent David, and followed Director Shepard inside the car. Once they were all settled, Ziva started up the engine of the car, and drove insanely out of the parking lot. Director Shepard's smile looked forced now, and Charlie couldn't help but notice that her knuckles had quickly turned white.

"I hope my driving isn't too scary for you, Charlie," Ziva noted, though she didn't bother to slow down.

"No problem. I guess I've gotten used to it, having a fed for a brother and living in L.A. Though, I'm a little used to the sirens being on, or at least the flashing lights."

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"DiNozzo! McGee! Where is he?"

Tony DiNozzo looked up from his desk, where he was filling out paperwork. "Boss, Doctor Eppes' plane only landed half an hour ago."

"So why wasn't he here fifteen minutes ago? Is the Director treating him to breakfast or something?"

"Well, Boss, often times, people don't get out of the airport as long as forty-five minutes after the plane lands. And then there is probable traffic during rush hour…" McGee informed him.

"Yeah, like traffic is going to stopped Ziva," Tony commented, remembering all the times he had been in the car while she was driving. "Who knows, she might have killed them all with her driving."

"Very funny, DiNozzo. Let me know when the doctor is in, alright?"

"No need, Jethro. We are here."

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The ride on the elevator was spent in uncomfortable silence. It seemed as though it took eons for the doors to finally open. Finally, the doors did open, and an angry voice said, "Let me know when the doctor is in, alright?" It had to be Agent Gibbs.

Director Shepard stepped out of the elevator in front of him, and replied, "No need, Jethro. We are here."

Ziva was carrying his suitcase again, although he had offered to carry it several times. Charlie and Ziva walked out of the elevator together towards the bullpen. There, an older man with graying hair stood in the middle of a few desks. On one side of him, two desks were occupied with men, each in their mid-thirties, Charlie guessed. On the other side of the man standing were two other desks, both empty.

"About time," Gibbs muttered under his breath, but it was still loud enough for Charlie to hear. He turned around to face Charlie. "Doctor Eppes. Good to see you. You've met Director Shepard and Agent David. This is Agent McGee," Gibbs pointed towards the man on the left, who Charlie figured had just been staring at the computer, given his hand was still on the mouse, "and this is Agent DiNozzo." This time he pointed to the man on the right, who was working on some paperwork, though he did look up and nodded in response to his name. "And I'm Agent Gibbs."

Charlie nodded. He wasn't quite sure how he should respond to Agent Gibbs' short introductions. Fortunately, he didn't have to, as Agent Gibbs spoke up again.

"Now that introductions are over, social time is also over. Ziva, take Doctor Eppes down to the lab. Abby has a desk down there ready for him."

"He goes by Charlie, Agent Gibbs," Ziva interjected.

"Fine. Take _Charlie_ down to the lab. Abby has a desk down there ready for him." Agent Gibbs turned back to Charlie. "Charlie, you are going to be set up down in the lab with Abby. You are allowed to go to the morgue, you can be up here, you can be in the lab, and if you ask one of the other agents to take you to crime scenes," his voice level raised, making sure that everyone heard him, "they will be more than happy to take you there. Got it?"

"Got it, Agent Gibbs," Charlie finally found his voice, and he followed Ziva before Agent Gibbs called him back.

"Oh, and Charlie? Make sure when you get down to the lab that you tell Abby that you are _not_ her assistant, you are simply working with the entire team. She's had some bad experiences with her previous assistants, and if she thinks you are one, she'll bite your head off when you enter the room."

Charlie nodded again. "Got it. Anything else?"

"Nope, that's it. Welcome to the team, Doctor Eppes." As Gibbs sat down at his desk, Charlie couldn't help but notice he had used his full title. _Maybe as a rite of passage of sorts?_ Hopefully, it wouldn't be a passage from bad to worse.

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"Don! You're here early," Megan commented.

Don smiled at her. "Can't be talking much yourself, Reeves. I figured I would be the first one here, given it's only six o'clock. What's going on?"

"Couldn't sleep, and I figure there was no point at staying at home when there's work to be done here. How's Charlie?"

Don was caught aback at the fact that she switched the conversation quickly to Charlie. "He's fine. He was a little worried about going off to D.C. so suddenly, but he got on to the plane all right. Why do you ask?"

"Well, just the way you were acting while on the phone yesterday clued me in. You, the protective older brother, wouldn't give his information out, even though it was to NCIS. I'm guessing he was wanted to consult for them as he does for the FBI, because I can't imagine Charlie doing anything illegal. So why were you so worried?"

"It's not so much about him heading to D.C. It's more about the fact that he'll be working with some Agent Gibbs. Charlie seems to think that Agent Gibbs is mad at him for some reason, even though they've never met."

"Well, that doesn't mean that you should be worried about him. He's an adult now, Don. He can't have you protecting him all the time," she reasoned.

"He may be an adult, but I don't think he's fully grown up."


	4. Chapter 4

**Disclaimer:** Abby, Dr. Mallard, Ziva, Jimmy, and Gibbs are part of NCIS, and Charlie and his brother are part of Numb3rs. Both belong to CBS and its affiliates. The victims' names and descriptions are all figments of the author's imagination. Any reference to any real person or persons is merely coincidental and accidental.

**A.N.** I am SO sorry everyone! I really didn't mean to keep you all waiting for this chapter! But with bad grades, stress, life, and writer's block, it took much longer that I had been planning. I hope I haven't discouraged too many people from continuing to read this, and I will try (but not promise-sorry!) to update a little sooner and more regularly than this time.

Also, special thanks to my math teacher from this past year for helping me figure out all of the calculations that are going to be used throughout the story, and for my friend Miomo for staying on my back to update this lately.

Again, thanks for your patience everyone, and enjoy the chapter!

… … … … … … … … … …

She couldn't believe it. With all the trouble Chip brought to the team, Gibbs was hiring another assistant? The team didn't know anything about this Doctor Eppes guy. All they knew was that this guy was a mathematical genius, and he had a brother in the FBI, which he sometimes consulted for.

Sitting back in her chair, drinking her Big Gulp, Abby Sciuto tried to imagine what he must look like, given the name and background information. He taught math at Cal Tech-or was it Cal Sci?- so she figured he was an uptight guy, wearing a business suit everyday. He grew up with his brother, who ended up being the leader of the FBI office out of LA. So he probably did have a sense of humor that came out occasionally, if he was anything like Gibbs. He probably would talk like he was superior to everybody, making everyone call him "Doctor Eppes." Abby shuddered at the thought. Having an assistant is bad enough. But an uptight guy as an assistant? Could it get any worse?

The elevator made its "ding" sound, and Abby turned around to get her first glance at the infamous Doctor Charles Eppes.

She was blown away by what she saw.

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Another elevator ride later, Charlie entered the lab with Ziva next to him, still carrying his suitcase for him. Looking around at he lab, he was impressed with all the equipment he saw, and of the arrangement of the room.

Sitting in the midst of the room was who he presumed was Abby. But she looked nothing like what he was expecting. He expected someone in a white lab coat, a dress shirt sticking out from underneath the coat near the neck. Instead, this woman was wearing a simple white tank top and black pants, but it was more her head that threw Charlie off balance. Her black hair was up in pigtails, she was wearing dark red lipstick, and her face was incredibly pale. What especially startled Charlie was the fact hat she had a tattoo of a spider'sweb on her neck.

"Abby, this is Doctor Eppes, but he goes by Charlie."

And before Charlie knew it, Abby had stood up, ran over to him, and gave him a bone-crushing hug, exclaiming, "I'm so glad you are nothing like what I imagined you to be!"

To say that he was shocked was an understatement.

… … … … … … … … … …

Abby pulled away from the hug, her grin spreading from ear to ear. _Well, if this Is the assistant, it can't be too bad_, she thought. Her smile faded only slightly when she saw that his eyes were as wide as saucers, and his jaw had dropped.

"I'm sorry, did I scare you, Doc?"

Charlie regained his composure, and his facial features resumed to normal. "More like startled me, Abby. And, as Ziva said, you can just call me Charlie."

"I know what she said. It's just much cooler to call you Doc," she replied cheerfully.

The two of them continued to look at each other in silence before Ziva broke it. "Abby, where would you like me to put Charlie's thinkgs?"

"The desk in the corner is fine. I cleaned it off for him earlier today," Abby said without looking at her. Instead, she continued looking at Charlie. "So, Doc," she grabbed him by the arm and led him over to the large screen, "I'm guessing that you want to be briefed about the case, huh?"

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Abby finally turned away from Charlie, although her hand was still on his arm. She brought up the images on the screen with the numerical patterns from the crime scenes.

"We have had 2 victims that were part of the marines, but there was another guirl that was found, a civilian," Abby stated. "We don't know yet if the killer is after women in the marines, or it's jut a coincidence.

"Nothing is a coincidence," Charlie interrupted.

"Don't say you're as bad as Gibbes on that opinion," Abby responded without missing a beat.

Charlie could hear Abby coninue talking, but his brain was no longer processing her voice. _Am I really that similar to Agent Gibbs?_ He wondered. _Is he as nit-picky about people saying there a coincidences in the world as I am?_

"Doc? Are you still listening?"

"Yeah, yeah, I'm listening, Abby. Listen, I would like to see the bodies, and then I'll look at the numbers, okay?"

Abby looked a little taken aback. "Sure. If you think that will work, go ahead."

"I'm going to need a guide to the morgue, though." Charlie looked around, and saw that Ziva had already left the lab. "And as you're the only one here who knows their way around the building…" Charlie raised his eyebrows expectantly at Abby.

Abby hesistated before replying, but when she did, she was as cheerful as ever. "Well, Doc, I'd be glad to show you down to the morgue."

… … … … … … … … … …

"Now, Jimmy, be careful with that heart. We don't want to break it, as I'm guessing some of her old boyfriends must have," Dr. Mallard instructed his assistant.

Jimmy grinned as he loosed his grasp on the heart he was carrying from the body in autopsy. "Your wit never ceases to amaze me, Dr. Mallard."

Ducky heard the door open behind him, but he didn't turn around to see who it was. _Who else could it be besides Jethro, anyway?_ "Jethro, I was waiting for you to come down. I've almost finished the autopsy on our Jane Doe here.":

"Actually, Ducky," Abby's voice responded, "We don't care much for Jane here. I brought Doctor Eppes, the new consultant, down. He wants to take a look at the bodies from the other case.

Ducky would have whipped around, had he not had his hands stuck inside a dead body on the table. "Doctor Eppes? As in, Doctor Charles Eppes?" He finally pulled his hands out of the body in front of him and slowly turned around.

"Yep, that's me, Duck." A slightly childish grin grew on the goung man's face. "How have you been?"

"Never better, Charles."

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Doctor Eppes? As in, Doctor Charles Eppes?"

Charlie was slightly surprised to hear Doctor Mallard ask if it was truly him. _Perhaps they didn't tell him. But why? _"Yep, that's me, Duck," Charlie greeted the old aquaintance. A grin spread across his face, and as much as he tried to stay at least a little serious, he was sure it looked pretty goofy. "How have you been?"

"Never better, Charles." Ducky pulled his bloody gloves off and threw them in the waste bin before offering a hand to Charlie. "And you?

"Same here." The grin refused to leave his face as he shook the hand held towards him. "It's been much too long since we last met, though."

Abby interrupted the reunion to ask, "Are you two trying to tell me that you know each other?

"It was several years ago, Abigail," Ducky began. Charlie was pleased to notice that he wasn't the only one Ducky called by his full first name.

"Around ten years ago, actually. We were at a convention of sorts, for different sciences," Charlie continued.

"Was it really? Has it truly been that many years?" Ducky asked, clearly astonished.

Charlie nodded. It had been. He could remember going like it was yesterday, though. A simple weekend conference in Las Vegas for scientists of different fields. Larry had somehow convinced Charlie along, thinking it would be a good experience for him, as well as a chance to get out of his garage for a week. His whole family seemed to be for the idea as well.

"_Come on, Charles. Your talent would be helpful for some of the scientists there. The whole idea of the conference is to share different ideas and connect all of the scientists together. Your knowledge of mathematics is sure to bring insight into some of their projects, and the chances are high that you'll learn something yourself."_

Indeed, he had learned new facts there. No one gave him so much interesting information as Doctor Donald Mallard, though. And he seemed to be interested in Charlie's math.

"_Someday, Charles, I'm sure you will become known for your work. Not just for your math itself, but also for how it helps thosse that wish to believe that it has no use to them. And when you do, you'll have to come back and tell me all about it."_

"So you've convinced people that your math can be used?" Dr. Mallard asked him. "I daresay it will help with this case. Let me show you the bodies, then."

"While you do that, Ducky, I'm going to head back upstairs." Charlie turned around in time to see Abby make a quick exit from the room.

"We currently have three victims, all female. Two of them were Marines, and one of them is a civilian. We don't know if the killer is going after service women or not, although we're guessing he doesn't have a preference one way or another." Ducky rolled out each body, one by one, as he was talking. "All of our victims were strangled with sturdy rope, although it wrapped all the way around the neck."

Charlie walked around, inspecting all the bodies. "They were strangled, you say?

"Yes. We collected rope fibers, and found that the rope used comes from any standard hardware supply store. We couldn't trace to which one it was."

Charlie pointed to the neck of one of the girls. "Then why is her throat slit?"

"That was performed post-mortem, Charles, possibly to cover up the bruising from the strangulation. The girls experienced no knife cutting into them when they were alive."

Charlie nodded as Ducky continued. "Each of the girls came with a note, including the non-marine. It makes me wonder whether our killer was specifically going after marines or not."

"What was the order of the girls' deaths?"

"The first one, Carrie Maskovy, is the blonde girl over there. She was one of our marines. The second one was also a marine, Lily Small, the brunette on this table. Our non-marine was the last of the three to be killed, Sasha Brewer," Ducky replied. "As I said, each girl came with a note, filled with numbers that none of us could make heads or tails out of. That's where you come in, I assume. Abby has those notes upstairs. I don't think there is much more I can do for you down here, Charles."

"Thanks, Duck. This has been very informative. And it's good to see you again."

"Same with you."

Charlie continued to process all of the other information as he headed back to the elevator, added to the attempt to remember what floor Abby was on.

_Why can I remember thousands of complex formulas and equations, but not what floor to get off at while on the elevator?_

… … … … … … … … … …

The doors to the lab opened, and once again, Doc came strolling into the room.

"Alright, Abby, I'm ready to see those notes that were found with the victims," he told her, not even fully across the room.

"I figured you would. I've gotten them out for you already."

Doc took the three of them and put them next to each other on the table, making sure both of them could read it. All of them were nearly identical.

_6.28_

_2/1_

_7_

_6_

The third to last line held the only differences. The first letter simply had a 5, the second, a 4, and the third letter, a 3.

The letters continued, once again identical in the numbers.

_36, 10_

_115, 10_

"It's not as cold as we thought," she heard him mumble before running back out of the room.

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Charlie couldn't believe his eyes. The papers weren't making entire sense, but he knew that something was up.

Running for the elevator again, Charlie tried to figure out what to tell Agent Gibbs. As a familiar _ding_ sounded, he almost ran into the exact person he was looking for.

"Agent Gibbs, the numbers that Abby showed me. They are the same as the case we just worked on in Los Angeles."

"What do you mean?"

"The notes that we got on our last case there were almost exactly the same as the ones that are here. I never saw the bodies there, but I'm willing to bet they have the same injuries as the three women that died in this area."

"Are you saying that this killer has been moving from area to area to commit these acts?"

"I think so, Sir."

"And you had a cold case there?"

"That's right. Fortunately and unfortunately, we didn't have enough information to find the guy. We now have more data to examine."

Agent Gibbs paused for a single second before giving his next order. "Call your brother. Tell him to get onto the next flight out, and bring the information from the last case with him. The more people that are working together to nail this guy, the better."


End file.
